This raises the JSON-RPC batch request limits significantly for the engine API endpoint.
The limits are now also hard-coded, so users won't get them wrong. I have chosen these limits:

    maximum batch items: 2000
    maximum batch response size: 250MB

While it would also be possible to disable batch limits completely for the engine API, 
I think having some limits is a good safety net against misbehaving CLs. Since this
 isn't configurable, we really want to ensure this limit will never become an issue in the
 CL/EL communication, so I set them quite high.

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Signed-off-by: jsvisa <delweng@gmail.com>
Co-authored-by: Felix Lange <fjl@twurst.com>